help with #define

[urundead]

I need to do something like this:

#define ACTIVATE_MODE(x) mode#x();

void mode1();
void mode2();

int main(){
int i;
cin >> i; // i = 1
ACTIVATE_MODE(i)
return0;
}

so ACTIVATE_MODE(i) --> mode1();
Thank You!

[helios]

That's not possible with macros, but there are other alternatives:

#include <iostream>
#include <stdexcept>

typedef void(*fp)();

void mode1();
void mode2();

void dynamic_mode(int i){
    static const fp functions[] = {
        mode1,
        mode2,
    };
    static const size_t n = sizeof(functions) / sizeof(*functions);
    i--;
    if (i < 0 || i >= n)
        throw std::out_of_range();

    functions[i]();
}

int main(){
    int i;
    std::cin >> i;
    dynamic_mode(i);
    return 0;
}

[jonnin]

you can also just do this:
#ifdef use1 //set this in your project settings when you compile.
#define ACTIVATE_MODE(x) mode1();
#else
#define ACTIVATE_MODE(x) mode2();